Coil bobbins typically include a plastic core and a pair of plastic flanges arranged at opposite ends of the core. Terminal pins, which are usually made from tinned brass, extend outwardly from one flange or both flanges of the bobbin. One end of a piece of magnet wire is wrapped around one of the terminal pins. After wrapping the bulk of the magnet wire around the core of the bobbin, the other end of the magnet wire is wrapped around another terminal pin.
The terminal pins are adapted for insertion into holes in, for instance, a printed circuit board. Prior to inserting the pins into the holes of the printed circuit board, the magnet wire must be permanently attached to the pins. In the past, such attachment was accomplished by inserting the pins into a solder bath. The solder bath technique is disadvantageous because the heat generated by the bath can cause the plastic flanges of the bobbin to melt, thereby loosening the terminal pins. Also, when the soldered terminal pins are resoldered during their attachment to the printed circuit board, the heat generated during such resoldering could loosen the already soldered magnet wire.
Fusing is an alternate to soldering. Fusing the wire magnet to the terminal is, however, difficult because the insulation on the wire prevents electrodes used in the fusing operation from making a closed circuit. thus, in order to fuse the magnet wire to the terminal pins, the insulation must first be stripped off of the magnet wire. Such a stripping operation is tedious and time consuming. Also, because the magnet wire is directly contacted by the electrodes, the wire is carrying capability can be impaired to an extent sufficient to cause the wire to break, thereby completely destroying the current carrying capability of the wire.